Anterior Cruciate Ligament Injury: Non-operative Treatment and Post-operative Rehabilitation

Introduction: The anterior cruciate ligament (ACL) is an internal stabilizer in the knee joint, which limits anterior and posterior translation, and excessive rotational movement of the knee. The ACL most often ruptures in the early degrees of knee flexion during cutting or pivoting movements. Treatment varies between patients depending on factors such as age, knee-joint laxity, and patient expectations. Patients are treated with ACL rehabilitation, with or without additional reconstruction of the injured ACL. Today, about half the patients who sustain an ACL injury are treated with ACL rehabilitation alone in Scandinavia, although approximately 50% of these patients subsequently choose to undergo additional ACL reconstruction due to insufficient knee function. Non-operative Treatment: Patients who have ≤1 on the Lachman test and pivot-shift test have a fair ability to attain reasonable knee function with non-operative treatment. The aim for patients electing to undergo non-operative treatment should be to improve post-injury acute impairments and regain muscle strength in order to ensure participation in the desired activities, minimizing the risk of episodes of functional instability or giving-way, which could expose patients to the risk of secondary injuries such as meniscus or cartilage injuries. Prior to a return to sports, patients treated with rehabilitation alone are advised to complete a 10-session program to ensure the safest return possible, i.e., without sustaining further knee injuries. Although structured rehabilitation is the treatment for this patient group, many struggle to regain acceptable knee function and joint stability, resulting in reduced physical activity, lower self-efficacy, and poorer quality of life than prior to injury. Post-operative Rehabilitation: In the early stages of rehabilitation after ACL reconstruction, patients treated with rehabilitation with additional ACL reconstruction may experience increased pain, range of motion deficits, and swelling in the knee joint. In the early phase, rehabilitation aims both to improve range of motion and to reduce pain and swelling in order to start strength training. Post-operative rehabilitation further aims to recover muscle strength and function (i.e., both absolute muscle strength and symmetrical function), in order to ensure a safe return to physical activity, without sustaining a second ACL injury. In addition, the psychological aspect of rehabilitation needs to be considered as both a strong and weak psychological profile can increase the risk of a second ACL injury. To address this issue, meeting return to sport (RTS) criteria consisting of strength, hop tests, and patient-reported outcomes has been shown to reduce the rate of subsequent knee injuries at the time of RTS. Summary: An ACL injury is a severe knee injury causing increased knee laxity and functional impairments. Regardless of additional ACL reconstruction or not, rehabilitation aims to recover muscle strength and function so that patients can return to their planned physical activity.